inet_addr()的功能是將一個點分十進制的IP轉換成一個長整數型數（u_long類型）
基本介紹
- 中文名：inet_addr()函式
- 別稱：IP位址轉化函式
- 表達式：inet_addr(const char *cp);
- 套用學科：計算機編程，C++
- 適用領域範圍：網路
- 功能：點分十進制IP轉換網路位元組序IP
基本介紹,英文原意,基本注釋,基本要求,編程舉例,
基本介紹
原型：in_addr_t inet_addr(const char *cp);
參數：字元串，一個點分十進制的IP位址
返回值：
如果正確執行將返回一個無符號長整數型數。如果傳入的字元串不是一個合法的IP位址，將返回INADDR_NONE。
頭檔案：
Winsock2.h (windows)
arpa/inet.h (Linux)
英文原意
The Windows Sockets inet_addr function converts a string containing an (Ipv4) Internet Protocol dotted address into a proper address for the IN_ADDR structure.
unsigned long inet_addr(const char FAR *cp );
Parameters
cp
[in] Null-terminated character string representing a number expressed in the Internet standard ".'' (dotted) notation.
Return Values
If no error occurs, inet_addr returns an unsigned long value containing a suitable binary representation of the Internet address given. If the string in the cp parameter does not contain a legitimate Internet address, for example if a portion of an "a.b.c.d" address exceeds 255, then inet_addr returns the value INADDR_NONE.
Remarks The inet_addr function interprets the character string specified by the cp parameter. This string represents a numeric Internet address expressed in the Internet standard ".'' notation. The value returned is a number suitable for use as an Internet address. All Internet addresses are returned in IP's network order (bytes ordered from left to right). If you pass in " " (a space) to the inet_addr function, inet_addr returns zero.
